Alkyl-aralkyl-cellulose esters and process of making them



Patented Nov. 24, 1931 UNITED STATES PATENT OFFICE ms'r m, 01' DO BIAGIN, em, ASSIGNOR '.l.'0 IIL'G. IARBENINDUSTRIE AITIENGEELLSCHAFT, OF IBANmBT-ON-THE-IAIN, GERMANY, A CORPORATION 'nm-mAI-mcnmunosn Esme m rnocnss or naxme rnnlr Io Drawing. Application fled January 10, 1880, Serial No. 420,021, and in Germany January 21, 1929.

The present invention relates to the manufacture of alkyl-aralkyl-cellulose esters and I to the new products obtainable thereby.

methyl and ethyl celluloses are made use of,

are very readily and usually completely soluble not only in cold water, ut also in boiling water whereby they lose so muchmaterial (30% and more), that the process is rendered very expensive; Furthermore, when working on a technical scale, a partial coolin (for example coolin due to evaporation? can hardly be avoi ed. Before the alkylcelluloses are completely dry, they swell up under the influence of cold water, agglomerate or cake and then form lumps which are impermeable to the acidylating mixture. Thus,

although the extraordinary ease with which the incompletely a lated celluloses can be further acidylated, o ers a great advantage, there is little success when carrying out the process on a large scale. I

In accordance with the present invention, this disadvantage is overcome by esterifying witha fatty acid containing not more than 4 carbon oms an incompletely alkylated cellulose'con aining in mixture a small amount of an aralkyl cellulose, such as benzyl cellulose, by acting upon said cellulose ether with the anhydride of the fatty acidto be introduced in the presence of the free fatty acid as solvent and of an acylation catalyst; for

- it has been found that the solubility in water or swelling power of the alkylcelluloses, containing to 1% mol of an alkyl group per one mol orf'C H O is eliminated, when the alkylcelluloses contain in admixture-a small aralkyl percntage of aralkyl'cellulose, such as benzyl-, romobenzyl-, nitrobenzyL. or toluyl-cellu-- lose, a content ofonly 2% of aralkyl cellulose being suflicie'n It is immaterial whether the aralkyl ether is produced together with the alkyl ether in a single process, in which the etherifying agent introducing the group, such as benzyl chloride, is added to the alkylating mixture, or whether the alkylating agent is caused to react on the finished, incompletely alkylated cellulose compound.

The amount of the aralkylating agent, such as benzyl chloride, to be added may range from;1/2O to ,4; of one molecular proportion, advantageously being of'one' molecular proportion, calculated on the G l-I 0 molecule.- -Taking into consideration the saponification of the aralkyl halogenide to the corresponding alcohol,.there is obtained,

that they can be washed free from salts and alkalies without loss. For example, for 100 parts by weight of cellulose, 115 parts by weight of monethyl cellulose (containing.

about 1% benzyl cellulose) are obtained,

while the calculated amount is 117 parts by weight; -The swelling is so small even in ice water, that an agglomeration or sticking to- 1 gether of the swollen fibers no longer takes place ,andan easy penetration with the acetylating mixture is secured. The acidylation is not afiectedby the aralkyl content. In the alkyl-aralkyl-ester finally obtained the efl'ect of the aralkyl content is'shownby the de crease in the degree of swelling in water of, for example, a 1-ethyl-1 -acetyl cellulose, containingfabout 1% of benzyl cellulose, falling from about 1.5% to less than 0.5%. With this is associated an excellent stability to boil ing of the and artificial threads prepared therefrom.

1 The invention isillustrated by the'following example but is not-restricted thereto:

Exemplarparts by weight of cellulose v (cotton orjwood pulp). are soaked with an aqueous caustic soda solution of 30 per cent strength, pressed to 2 times the above weight, mixed with 100 parts by weight of ethyl chloride and 14 parts by weight of benzyl chloride mol. calculated on C' H10O5) and heated for 3 hours at 110. C. The reaction product is Washed free from salts and alkalies by means of water and dried. 115 parts by weight of a monoethyl cellulose (containing about 1% benzyl) are obtained. 7

To 100 parts by weight of this monoethyl cellulose 160 parts by weight of acetic anhydride, 500 parts by weight of acetic, acid and 1 part by Weight of sulfuric acid are added and acetylation is effected with slow heating to 30 C. for two hours in a suitable apparatus. Thereupon the ether-acetate is precipitated directly with water without hydrolyzing and washed free from acid.

A monoethyl-l -acctyl cellulose containing about 1% of benzyl cellulose, is obtained, which is soluble in acetone, acetic ester and chlorinated hydrocarbons and yields very clear and strong films and is particularly suitable for the manufacture of artificial threads. The stability to water of the latter surpasses that of all other artificial silk materials.

I claim:

1. In the process of preparing alkylaralkyl-cellulose esters, the step which comprises esterifying by reacting with the anhydride of the fatty acid to be introduced in the presence of the free fatty acid as solvent and of an acylation catalyst upon an alkylaralkyl-cellulose'*iii whichabout fi l hydroxy groups calculated on the molecule C l-L 0 are etherified and containing about A;-2% of aralkyl-cellulose.

2. In the process of preparing alkylaralkyl-cellulose esters, the step which comprises esterifying by reacting with the anhydride of the fatty acid to be introduced in the presence of the free fatty acid as solvent and of an acylation catalyst upon an alkyl-benzylcellulose in which about. 1 hydroxy groups calculated on the molecule C-gH Os are etherified and containing about 2% of benzyl-cellulose.

3. In the process of preparing alkylaralkyl-cellulose esters, the step which comprises esterifying by reacting with the/anhydride of the fatty acid to be introduced in the presence of the free fatty acid as solvent and of an acylation catalyst upon an ethyl-benzylcellulose in which about 5-1 5 hydroxy groups calculated'on the molecule (3 1L 0 are etherified and containing about 2% of benzyl-cellulose. I

4. In the process of preparing alkylaralkyl-cellulose esters, the step which comprises acetylating by reacting with acetic anhydride in the presence of acetic acid and an acetylation catalyst upon an alkylgroups calculated on the molecule aralkyl-cellulos in which about 1 hydroxy groups calculated on the molecule- C H O are etherified and containing about 2% of aralkyl-cellulose.

' benzyl-cellulose.

- 6. In the process of preparing alkylaralkyl-cellulose esters, the step which comprises acetylating by reacting with acetic an acetylation catalyst upon an ethyl-benzylcellulose in which about /g-IJ/z lydroxy e io s are etherified and containing about 1% of benzyl-cellulose.

7. As new products alkyl-aralkyl-cellulose esters in which about 2 hydroxy group calculated on the molecule G H O are substituted, obtainable in accordance with a process as claimedin claim 1 being generally soluble in acetone, acetic ester and chlorinated hydrocarbons and yielding very .clear and strong films and artificial threads substantially stable to water.

8. As new products alkyl-benzyl-cellulose esters in which about 2% hydroxy group calculated on the molecule C l-L 0 are substituted, obtainable in accordance with a process as claimed in claim 2, being generallysoluble in acetone, acetic ester and chlorinated hydrocarbons and yielding very clear and strong films and artificial threads substantially stable to water.

9. As new products ethyl-be'nzyl-cellulose esters inwhich about 2 hydroxy group calculated on the molecule CGH O are substituted, obtainable in accordance witha process as claimed in claim 3, being generally soluble in'acetone, acetic ester and chlorinated hydrocarbons and yielding very clear and strong films and artificial threads substantially stable to water.

o 10. As new products alky'l-aralkyl-cell'ulose acetates in which about 2 hydroxy group calculated on the molecule C H O are substituted, obtainable in accordance with a process as claimed in claim 4, being generally soluble in acetone, acetic ester and chlorinated =anhydride in the presence of acetic acid and a hydrocarbons and yielding very clear and strong; films and artificialthreads substantially stable to water.

11. As new products alkyl-benzyl-cellulose acetates in which about 2 hydroxy group calculat d on the molecule O I-L 0 are substituted, obtainable in accordance with a process as claimed in claim 5, being generally soluble in acetone, acetic ester and chlorinated hydrocarbons and yielding very clear and strong and artificial threads substantiaIly stable to water. 4 y 12. As a new product an ethyl-benzyl-cellulose acetate in which about 2% lydroxy 5 groups calculated-on the molecule H 5 are substituted, obtainable in accordance with a process as claimed in claim 6, being generally soluble in acetone, acetic ester and chlorinated hydrocarbons and yielding very 10 clear and strong films and artificial threads 7 substantially stable to water.

In testimony whereof, I afiix my signature.

ERNST TEUPEL. [L. 5.]- 

